In electronic media management systems it is desirable to detect the orientation of consumer photographs and other images stored in digital format so that the digital images can be stored and/or retrieved in their correct orientation. Manually retrieving, viewing, and orienting large numbers of digital images is very time-consuming, and is accordingly an impractical undertaking. Not surprisingly, techniques for automatically determining orientation of digital images have been considered.
For example, U.S. Pat. No. 6,512,846 to Luo discloses a method, image recognition system and computer program for determining image orientation. Potential sky pixels in the image are classified by color and spatially contiguous regions of the potential sky pixels are identified. Actual sky regions are identified by eliminating ones of the spatially contiguous regions that have a texture above a predetermined texture threshold and desaturation gradients of the actual sky regions are computed. The image is classified as one of portrait and landscape based on average absolute values of horizontal and vertical desaturation gradients of pixels within each of the actual sky regions. Orientation of the image is determined based on a polarity of the average horizontal and vertical desaturation gradients, and the actual sky regions are confirmed as true sky regions by comparing the desaturation gradients with a predetermined desaturation gradient for sky.
U.S. Pat. No. 5,842,194 to Arbuckle discloses a system comprising a neural network, or computer, for implementing a feature detection and a statistical procedure, and fuzzy logic for solving the problem of recognition of faces or other objects at multiple resolutions. A plurality of systems for recognizing faces (or other objects) which use local autocorrelation coefficients and linear discriminant analysis are trained on a data set to recognize facial images each at a particular resolution. In a second training stage, each of the systems is tested on a second training set in which the images presented to the recognition systems have a matching resolution to those of the first training set. The statistical performance of the second training stage is used to train a fuzzy combination technique, that of fuzzy integrals. In a test stage, the results from the classifiers at the multiple resolutions are combined using fuzzy combination to produce an aggregated system whose performance is higher than that of any of the individual systems.
U.S. Pat. No. 6,915,025 to Wang et al. discloses arrangements and procedures for identifying an image's orientation by extracting features from peripheral portions of the image. The procedure evaluates the extracted features based on training image feature orientation classification models to identify the image's orientation.
U.S. Patent Application Publication No. 2003/0152289 to Luo discloses a method for determining the orientation of a digital image. A semantic object detection method is employed to detect the presence and orientation of a semantic object. A scene layout detection method is employed to detect the orientation of a scene layout. An arbitration method is employed to produce an estimate of the image orientation from the orientation of the detected semantic object and the detected orientation of the scene layout.
U.S. Patent Application Publication No. 2004/0151371 to Chen et al. discloses a digital image processing method for determining an orientation of a face in a digital color image which generates a mean grid pattern element image from a plurality of sample face images and an integral image from the digital color image. A face is located in the color digital image by using the integral image to perform a correlation test between the mean grid pattern element image and the digital color image at a plurality of effective resolutions. The digital color image is reduced to a plurality of grid pattern element images at different effective resolutions and the mean grid pattern element image is correlated with the plurality of grid pattern element images. Either the mean grid pattern element image or the grid pattern element images are provided at a plurality of different orientations. The orientation of the face in the color digital image is determined by using the images with different orientations in the correlation test.
U.S. Patent Application Publication No. 2005/0261573 to Satoh et al. discloses an index detector which detects image coordinates of indices arranged on a scene from an image shot by an imaging device. An orientation sensor is attached to the imaging device, and outputs a measured orientation. An orientation prediction unit predicts an orientation of the imaging device on the basis of the measured orientation obtained by the orientation sensor. A position/orientation calculator receives the predicted orientation of the imaging device and a set of the image coordinates and world coordinates of each index, determines the position of the imaging device and an update value for an azimuth-drift-error correction value of the orientation sensor, and calculates the position and orientation of the imaging device.
U.S. Patent Application Publication No. 2005/0264658 to Ray et al. discloses a method for determining the presence of a face from image data which utilizes at least two algorithms. The first algorithm prescreens the image data by determining a plurality of face candidates utilizing a pattern matching technique that identifies image windows likely to contain faces based on color and shape information. The second algorithm processes the face candidates determined by the first algorithm, and uses a posterior probability function classifier to determine the presence of the face.
U.S. Patent Application Publication No. 2006/0083441 to Huang discloses a method for re-orientating digital images in an image-editing environment, where images are loaded in a landscape mode by default, with the aim of unburdening users from the inconvenience of manual correction of image orientation. Intelligent re-orientation of digital images is realized by analyzing an image in order to determine if re-orientation is required. This is accomplished in one embodiment by using image zone analysis processes and facial feature analysis.
U.S. Patent Application Publication No. 2006/0061599 to Yu et al. discloses (i) systems and methods for visually rendering images at a time of display based on annotations indicating needed rotations; (ii) systems and methods for visually rendering images at a time of display by determining a needed rotation for an image based on automatic orientation recognition; (iii) systems and methods for visually rendering images at a time of display by utilizing fuzzy logic to determine a best rotation angle for an image based on a non-precise marking generated by computer vision or signal processing applied to the image; and (iv) systems and methods for annotating images at the time of image capture, the time of image display, or any time in between by using one or more of automatic image orientation recognition, user input specifying a needed rotation, and sensed orientation of an image capture mechanism.
U.S. Patent Application Publication No. 2006/0067591 to Guzzwell et al. discloses a method, system and computer program product for identifying an orientation of an image having a plurality of features. The method comprises the steps of defining a plurality of feature kinds, wherein each feature in the plurality of features corresponds to an associated feature kind in the plurality of feature kinds and providing a feature kind classification order for ordering the plurality of feature kinds. The method also comprises searching the image to identify a feature set in the plurality of features in the image based on the feature kind classification order, wherein the feature set comprises at least one feature and each feature in the feature set corresponds to a defining feature kind. The feature set is classified to determine the orientation of the image.
Although the above references disclose techniques for orienting digital images, improvements are desired. It is therefore an object of the present invention to provide a novel method, system and computer readable medium embodying a computer program for automatically determining the orientation of a digital image.